Among the various comorbidities that affect patients with multiple sclerosis, motor symptoms, more frequently seen in the lower extremities than in the upper, result in an increase in significant problems with mobility among patients with MS. Frequently, lesions occur in the descending motor tracts of the spinal cord and may cause spasticity, including extensor spasms of the leg or trunk that are exacerbated by either active or passive attempts to rise from a sitting position.

On physical examination, spasticity is more notable in the legs than the arms, and the deep tendon reflexes may be exaggerated, with sustained clonus and extensor plantar responses. These physical findings are normally asymmetrical. There are occasional decreased deep tendon reflexes in the case of a lesion, which interrupts the reflex arc at a segmental level. Additionally, an inverted triceps reflex occurs when triceps contraction is diminished or absent, with the efferent component of the reflex represented by contraction of the biceps muscle. Lesions of the sacral segments of the spinal cord may result in loss of the Achilles reflex, a sign that may be accompanied by sexual dysfunction or sphincter problems. Lesions in the cerebellar pathway result in reduced reflexes and hypotonia.

The small muscles of the hand may be affected by amytrophy related to disuse, and lesions of the motor root exit zones may denervate muscles as a result of axonal loss. Another cause of muscular atrophy in multiple sclerosis is secondary entrapment neuropathy.

All of these findings contribute to significant difficulties with coordination. Gait imbalance is common and may require a cane or wheelchair. There may be difficulty in coordinated activity of the arms, with dysmetria, hypotonia, and decomposition of complex movements noted most frequently in the upper extremities, as a result of cerebellar pathway lesions. Intention tremors occur in the limbs or in the head, and truncal ataxia results in impaired gait. In severe cases of impairment, some patients experience astasia, or inability to stand. They may experience an inability to use their arms due to extreme tremor. 

Measures of disease progress include the Kurtzke disability scale and the expanded disability status scale; these scales are commonly used to measure progression of clinical disability in MS.2  The rate of progression among patients with multiple sclerosis is extremely variable.3 Recent studies suggest that progression is not rapid in most patients.4 A large longitudinal study following 2,319 patients in British Columbia observed the median time from onset of the disease to a level of disability where a cane was required for walking was 27.9 years.5

Treatment Strategies

The primary modality of treatment of the comorbid conditions associated with MS is treatment targeted at the inflammatory and demyelinating processes, but symptomatic treatment is the subject of this report. As noted, some patients with multiple sclerosis will require a cane or wheelchair. Physical therapy is a mainstay of treatment of gait problems in multiple sclerosis, coupled with the use of mobility aids when required.

Because spasticity may occur frequently in patients with multiple sclerosis, particularly in the legs, oral medications such as baclofen, tizanidine, and dantrolene are often used to ameliorate the effects of spasticity on mobility. A systematic study found fair evidence that these medications were effective when compared with placebo.6 Intrathecal baclofen infusions are one option for treatment of spasticity, and a review of evidence published by the American Academy of Neurology concluded that botulinum toxin is an effective therapy for reduction of muscle tone and improvement of passive movement in adults with spasticity.7 

Nonpharmacologic therapeutic options for spasticity in patients with multiple sclerosis include physiotherapy, structured exercise, electromagnetic therapy, transcutaneous electrical nerve stimulation, transcranial magnetic stimulation, and whole-body vibration.8 The evidence of effectiveness of these therapies is not strong. The effects of physiotherapy may improve mobility and has reportedly enhanced mood and subjective well being, but the effects appear to be transient.9

To improve walking speed in patients with multiple sclerosis, several trials have evaluated the effectiveness of dalfampridine, which is a potassium channel blocker. In the largest trial of randomly assigned adult patients with MS who were ambulatory, dalfampridine had a significantly higher proportion of patients who responded with faster walking speeds than those assigned to the placebo group.10

Subsequent trials resulted in approval of dalfampridine by the FDA for the indication of improvement of walking in patients with MS. 

Patients with MS may try a variety of complementary or alternative treatments, which include exercise, meditation, yoga, acupuncture, massage, vitamins, herbs, and mineral supplements. Cannabis is used by some patients with multiple sclerosis to relieve muscle stiffness.11 However, there is little data to support the use of these interventions.